A hard-fought presidential primary campaign is obscuring the uncharacteristic degree of unity within the Republican party. It has reached a conservative consensus on most of the pressing issues of the day. All of the leading candidates, and almost all of the lagging ones, support the right to life. All of them favor the repeal of Obamacare. Most of them support reforms to restrain the growth of entitlement spending. All of them favor reducing the corporate tax rate to levels that will make the U.S. a competitive location for investment. Almost all of them seem to understand the dangers of a precipitate withdrawal from Iraq and Afghanistan, and of a defense policy driven by the need to protect social spending rather than the national interest. Conservatives may disagree among themselves about which candidate most deserves support, but all of us should take heart in this development—and none of us should exaggerate the programmatic differences within the field.

Just as heartening, the White House seems winnable next year, and with it a majority in both houses of Congress, so that much of this conservative consensus could actually become law. A conservative majority on the Supreme Court, a halt to the march of regulation, free-market health-care policies: All of them seem within our grasp. But none of them is assured, and the costs of failure—either a failure to win the election, or a failure to govern competently and purposefully afterward—are as large as the opportunity.

We fear that to nominate former Speaker Newt Gingrich, the frontrunner in the polls, would be to blow this opportunity. We say that mindful of his opponents’ imperfections—and of his own virtues, which have been on display during his amazing comeback. Very few people with a personal history like his—two divorces, two marriages to former mistresses—have ever tried running for president. Gingrich himself has never run for a statewide office, let alone a national one, and has not run for anything since 1998. That year he was kicked out by his colleagues, the most conservative ones especially, who had lost confidence in him. During his time as Speaker, he was one of the most unpopular figures in public life. Just a few months ago his campaign seemed dead after a series of gaffes and resignations. That Gingrich now tops the polls is a tribute to his perseverance, and to Republicans’ admiration for his intellectual fecundity. Both qualities served conservatives well in the late 1980s and early 1990s, when Gingrich, nearly alone, saw the potential for a Republican takeover of Congress and worked tirelessly to bring it about. Even before the takeover, Gingrich helped to solidify the party’s opposition to tax increases and helped to defeat the Clinton health-care plan. The victory of 1994 enabled the passage of welfare reform, the most successful social policy of recent decades.

Gingrich’s colleagues were, however, right to bring his tenure to an end. His character flaws—his impulsiveness, his grandiosity, his weakness for half-baked (and not especially conservative) ideas—made him a poor Speaker of the House. Again and again he combined incendiary rhetoric with irresolute action, bringing Republicans all the political costs of a hardline position without actually taking one. Again and again he put his own interests above those of the causes he championed in public.

He says, and his defenders say, that time, reflection, and religious conversion have conquered his dark side. If he is the nominee, a campaign that should be about whether the country will continue on the path to social democracy would inevitably become to a large extent a referendum on Gingrich instead. And there is reason to doubt that he has changed. Each week we see the same traits that weakened Republicans from 1995 through 1998: I’d vote for Paul Ryan’s Medicare reform; Paul Ryan’s Medicare reform is radical right-wing social engineering; I apologize for saying that, and no one should quote what I said because I was wrong; actually, what I said was right all along but nobody understood me. I helped defeat Communism; anyone who made money in the ’80s and ’90s owes me; I’m like Reagan and Thatcher. Local community boards should decide what to do with illegal immigrants. Freddie Mac paid me all that money to tell them how stupid they were. Enough. Gingrich has always said he wants to transform the country. He appears unable to transform, or even govern, himself. He should be an adviser to the Republican party, but not again its head.

Gingrich is not the only candidate whom we believe conservatives should, regretfully, exclude from consideration for the presidency. Governor Perry has done an exemplary job in Texas but has seemed curiously and persistently unable to bring gravity to the national stage. Republican presidential candidates have not been known for their off-the-cuff eloquence in recent decades, but conservatism should not choose a standard-bearer who would have to spend much of his time untying his own tongue. Representative Bachmann’s rise early in the primary season reflected the public’s hunger for sincere conviction; her later descent, following among other things her casual repetition of false anti-vaccine rumors, its desire that conviction be married to judgment. Representative Paul’s recent re-dabbling in vile conspiracy theories about September 11 are a reminder that the excesses of the movement he leads are actually its essence.

Three other candidates deserve serious consideration. Governor Huntsman has a solid record, notwithstanding his sometimes glib foreign-policy pronouncements; his main weakness is his apparent inability, so far, to forge a connection with conservative voters outside Utah. Governor Romney won our endorsement last time, in part because some of the other leading candidates were openly hostile to important elements of conservatism. He is highly intelligent and disciplined, and he takes conservative positions on all the key issues. We still think he would make a fine president, but time and ceaseless effort have not yet overcome conservative voters’ skepticism about the liberal aspects of his record and his managerial disposition. Senator Santorum was an effective legislator. He deserves credit for highlighting, more than any other candidate, the need for public policies that topple barriers to middle-class aspirations. Weighing against him is a lack of executive experience.

As Republican primary voters consider their choices, they should ask themselves several questions: Which candidate is most likely to make the race turn on the large questions before the country, and not his personal idiosyncrasies? Which candidate is most likely to defeat Obama? Who could, if elected, form an effective partnership with Republican leaders and governors to achieve the conservative agenda? We will render further judgments in the weeks to come as the candidates continue to make their cases and are, just perhaps, joined by new candidates. At the moment we think it important to urge Republicans to have the good sense to reject a hasty marriage to Gingrich, which would risk dissolving in acrimony.